The four boys, who have been named as Ismael Mohammed Bakr, nine, Zakaria Ahed Bakr and Ahed Atif Bakr, both 10, and Mohammed Ramiz Bakr, were killed on the beach beside a coastal road west of Gaza City on Wednesday. Witnesses say the children fled after a first shell hit a nearby container, but died when a second rocket hit them.

Mark Regev, a spokesperson for the Israeli government, appeared on Channel 4 News to discuss the conflict. When presenter Jon Snow asked how “killing children on a beach” contributed to Operation Protective Edge’s stated purpose of protecting Israeli civilians, he simply responded: “It doesn’t”.

"Let me be clear here, the story with these four boys is a tragedy - you can't look at those pictures and not be moved - but let's be clear, the Israeli military does not target civilians,” he said.

“It does not target children, and I don’t believe the person who, if it was an Israeli, who fired and killed those poor boys knew that they were children.”

Mr Regev rejected the accusation that the Israeli military is deliberately targeting neighbourhoods where “you know there are women and children”. He said: “Hamas is using these urban areas where civilians are living their lives to shoot at us… They are shooting at Israeli’s, bombarding our towns, trying to kill our people.

One witness said the boys were scavenging for scrap metal when the first shell hit a nearby shipping container used in the past by Hamas security forces. He said the boys fled but a second rocket “hit all of them”.

Waiter Hussam Abadallah said the strike occurred at about 4pm, when he saw “white smoke coming from a small room, like a shack, belonging to one of the fishermen not far from the fishing port.”

He said he then saw the boys running. “We started shouting at them, 'run, run here,' then a shell from the sea landed behind them,” Mr Abadallah told the Associated Press.

Mr Snow suggested that despite Israel's sophisticated weaponry, the boys' deaths demonstrate it "cannot forensically attack without killing women and children - ergo, you have factored in that you will kill women and children".

Mr Regev responded: “The truth is, this is Hamas’s decision for shooting at us from these urban areas – that is a war crime, and they should be condemned for it."

The Israeli army said in a statement it was “carefully investigating” the matter. It said the target of the naval attack was “Hamas terrorist operatives” and that civilian casualties were “a tragic outcome”.

It said the army “has no intention of harming civilians dragged by Hamas into the reality of urban combat”.

The boys' uncle Abdel Kareem Baker, 41 has described their deaths as “a cold-blooded massacre”.

Israel and Hamas have begun observing a five-hour humanitarian ceasefire was due to begin today, following nine days of cross-border fighting which officials say has killed over 220 Palestinians and an Israeli.